Tire Pressure Monitor on my 2021 X1

[martybyrde]

I purchased a 2021 X1 a little over a year ago, and I am pleased with the vehicle. I recently bought it in for the required 1 year service, and everything checked out. However, I am encountering a "quirk" with the Tire Pressure Monitor (TPM). I'll try and explain.

According to the owner's manual, and the "plate" on the driver's side door panel, the cold air pressure for all 4 tires (they are Pirelli Run Flat tires) needs to be 33 psi. We don't drive the vehicle that much (has only 5000 miles on it), but I do try and keep a close eye on the tire pressure. When we are at home, the vehicle is always parked in the garage (as is our 2013 Toyota Camry). After I bought it in for service, I was surprised (and disappointed) when I used the TPM after the car had been in the garage for almost 2 days: 31 psi for all 4 tires! When I complained to the service advisor that "handled" my car, he apologized, mentioned it to the technician who performed the service on the X1 (including adjusting the tire pressure), and suggested that possibly the tool used for adjusting the tire pressure needed to be calibrated! That seemed to me to be a crock!

Fortunately, I have a portable "air pump" that I used to adjust the tire pressure up to 33 psi for all 4 tires. To confirm that, I again left the X1 in the garage overnight, and using the TPM the next day, it sure enough showed 33 psi for each tire.

Unfortunately, the TPM seems to be "quirky". In the past week, I have driven the vehicle 3 times (not on successive days), and between each "trip" (less than 40 miles total for each time), again the X1 has sat in the garage for 2 days. Yet the TPM does not show a consistent reading. On Monday, it showed 33 PSI for each tire. But on Wednesday, it showed a "mixture" of 32 psi and 33 psi. Yesterday the TPM showed a "mixture" again of 31 to 33 psi. Just a few minutes ago, I drove the X1 to the mail kiosk, and the TPM showed 32 psi for each tire. (Again, between each of those days, the X1 was parked in the garage, so the TPM was measuring COLD tire pressure).

Any ideas what gives? Can the psi fluctuate even with the X1 sitting in the garage most of the time? (I am located a little south of Seattle, and thus (for now), it is not bitterly cold).

[Qsilver7]

Yes…the inflation can fluctuate from various things….ambient temperature being one of them. Since air is a gas, it expands when heated and contracts when cooled. For example, every 10 degrees of increased temperature, your tires can be expected to increase by 1-2 pounds of pressure.

[gkski]

It is also true that sometimes valve stems need tone tightened.